1. Plate boundaries & convection currents

2. Quick Reminders
The Earth’s crust and upper mantle are broken into sections called plates
Plates move around on top of the mantle like rafts

4. What is the Lithosphere?
The crust and part of the upper mantle = lithosphere
100 km thick
Less dense than the material below it so it “floats”

6. 2 Types of Plates
Ocean plates - plates below the oceans (Basalt)
Continental plates - plates below the continents (Granite)

7. 3 Types of Plate Boundaries
Divergent
Convergent
Transform

8. Divergent Boundaries
Boundary between two plates that are moving apart or rifting
 

10. Type of Boundary: Divergent
Plate Mvmt: Moving Apart/ Rifting
Land form: Rift Valley/ small volcanoes
Ex) Iceland

13. Type of Bounday: Divergent
Plate Mvmt: Moving Apart/ Rifting
Land Forms:Mid-Ocean Ridge/ Sea floor spreading/ small volcanoes
Ex) Mid-Atlantic Ridge

14. Convergent Boundaries
Boundaries between two plates that are colliding
 
There are 3 types…

15. Type 1 Ocean plate colliding with a less dense continental plate
Subduction Zone: where the less dense plate slides under the more dense plate
VOLCANOES occur at subduction zones

17. Andes Mountains, South America

18. Type 2 Ocean plate colliding with another ocean plate
The less dense plate slides under the more dense plate creating a subduction zone called a Trench & Island Arc

20. Aleutian Islands, Alaska

21. Type 3 A continental plate colliding with another continental plate
Have Collision Zones:
a place where folded mountains form.

24. Transform Fault Boundaries
Boundary between two plates that are sliding past each other
EARTHQUAKES along faults

26. San Andreas Fault, CA

27. Questions... What are the three types of boundaries?
What direction do plates go for each?
Which boundary has a subduction zone…what occurs at a subduction zone?

28. Causes of Plate Tectonics

29. Convection Currents
Hot magma in the Earth moves toward the surface, cools, then sinks again.
Creates convection currents beneath the plates that cause the plates to move.

31. Questions... What causes plates to move?
How is a convection current formed?